Don't get me wrong, I'm not suggesting that a bumper sticker is justification for a high-risk traffic stop and I'm certainly not advocating that you point your TASER at someone because he/she has cauliflower ear. However, as trained observers, we can't afford to miss signs that alert us to potential danger.
Remember that spotting red flags is only half the battle. You also have to take appropriate action once you've identified a potentially dangerous situation.
If you allow someone wearing a martial arts uniform, sporting a black belt to get close enough to kick you in the head, shame on you! As the saying goes, "If it's predictable, it's preventable."